Capturing change in clonal composition amongst single mouse germinal centers

Area of Science:

• Immunology
• Cellular Biology
• Microscopy

Background:

• Studying cellular processes in vivo over extended periods (days to weeks) is challenging without disrupting tissue homeostasis.
• Longitudinal analysis of immune responses requires methods that allow repeated observation of the same tissue.

Purpose of the Study:

• To develop and validate a novel setup for longitudinal intravital imaging of murine peripheral lymph nodes (LNs).
• To visualize the formation and evolution of single germinal centers (GCs) over time scales of days to weeks.
• To investigate the dynamics of immune cell interactions and tissue remodeling within LNs with minimal perturbation.

Main Methods:

• Development of a specialized intravital imaging setup for murine peripheral lymph nodes.
• Longitudinal observation of germinal center formation and evolution in vivo.
• High temporospatial resolution imaging to track cellular dynamics and clonal composition shifts.

Main Results:

• Successfully visualized the formation and evolution of individual germinal centers (GCs) over days to weeks.
• Observed significant variations in homogenizing selection rates within GCs, even in close proximity.
• Documented greater GC fluidity than previously reported, with substantial clonal shifts and rare GC loss events.
• Identified contemporaneous, congruent shifts in clonal composition between GCs, suggesting memory B cell trafficking.

Conclusions:

• The novel imaging tool enables high-resolution, minimally perturbing longitudinal studies of immune dynamics in peripheral LNs.
• Germinal center dynamics are more fluid than previously understood, with significant clonal shifts occurring over short timescales.
• Evidence suggests inter-germinal center trafficking of memory B cells within the same animal.